The present invention relates generally to a method of removing contaminants from contaminated soil in situ and, more particularly, to such a method that employs a fluid impermeable barrier on the surface of the contaminated soil and a vacuum for drawing out the contaminants.
Increased environmental awareness has prompted concern over harmful and often irreparable contamination of natural resources. Contamination of soils and the underlying water table have posed particularly acute problems in recent years. Many sites are contaminated by accidental spills and dumping of hazardous liquids, such as organic solvents and hydrocarbons, which become absorbed by the soil and reside temporarily or permanently in the soil's interstices.
Contaminated soils such as these are generally useless to support vegetative and animal life, and often pose a threat to the surrounding ecosystems. In addition, an even more dangerous and pervasive threat exists in the possibility that such contaminants may flow hydrodynamically downward through the soil to the water table, rendering the immediate water unusable and spreading rapidly to contaminate surrounding water resources.
In the past, labor and capital intensive and time consuming excavation, decontamination and recovery procedures were employed to clean the soil and remediate the site. Such procedures often required digging shafts and underground conduits and flooding the contaminated area with suitable solvents. In addition, such excavation and flooding generally required drilling a bore so that the solvents and contaminants could run off into a reservoir for subsequent removal. Moreover, canopies and extensive exhaust systems were required to minimize atmospheric pollution or to remove contaminatd vapor flowing out of the contaminated soil as a result of the decontamination process. Moreover, while such procedures functioned reasonably well, they were not equally applicable to contamination in soils of different density, moisture contents and transmissivity.
The present invention overcomes many of the disadvantages inherent in the methods of decontamination described above by providing a method of drawing out contaminants from the soil while minimizing atmospheric leakage and hydrodynamic downward flow. In addition, the present invention may be employed in conjunction with soil areas of greatly varying density, moisture content and transmissivity. The methods of the present invention are greatly simplified over the prior art and, therefore, may be applied to contaminated soil areas quickly, easily and efficiently, with the result of considerable cost and time savings.